Constraints on radiative forcing and future climate change from observations and climate model ensembles

The assessment of uncertainties in global warming projections is often based on expert judgement, because a number of key variables in climate change are poorly quantified. In particular, the sensitivity of climate to changing greenhouse-gas concentrations in the atmosphere and the radiative forcing effects by aerosols are not well constrained, leading to large uncertainties in global warming simulations. Here we present a Monte Carlo approach to produce probabilistic climate projections, using a climate model of reduced complexity. The uncertainties in the input parameters and in the model itself are taken into account, and past observations of oceanic and atmospheric warming are used to constrain the range of realistic model responses. We obtain a probability density function for the present-day total radiative forcing, giving 1.4 to 2.4 W m-2 for the 5-95 per cent confidence range, narrowing the global-mean indirect aerosol effect to the range of 0 to -1.2 W m-2. Ensemble simulations for two illustrative emission scenarios suggest a 40 per cent probability that global-mean surface temperature increase will exceed the range predicted by the Intergovernmental Panel on Climate Change (IPCC), but only a 5 per cent probability that warming will fall below that range.     

基于禁忌搜索的神经网络集成

给出了一种利用禁忌搜索来实现神经网络集成AdaBoosting算法的方法。以Ada- Boosting算法中的权值向量为优化对象,对其若干个元素进行扰动,并通过设定其为禁忌对象,以禁忌搜索控制寻优方向,以逼近误差为适值函数,在满足逼近误差或达到进化代数时结束进化。由于禁忌搜索可以避免迂回搜索,从而提高进化效率,使得算法易收敛。通过实例验证了该方法的可行性。     

基于多层次模型的高等教育满意值探讨

高等教育的产品就是高等教育服务,该服务产品得到的满意值应与个人、家庭、国家的利益密切相关．文章把满意值分为宏观的满意值（国家与社会的满意值）和微观的满意值（个人与家庭的满意值）两个部分,在计算国家与社会的满意值和个体暂时的满意值时借鉴了已经成熟的评价体系和量化分析方法,在计算个体长远满意值时提出一种基于投影梯度Lagrange乘子的约束优化方法来构造增广函数,这种方法有效的避免惩罚函数方法带来的迭代收敛速度慢、工作量大、Hesse矩阵越来越病态的问题．这种方法可以较为有效的计算现阶段高等教育的满意值,得到要适当降低高等教育收费,提高高等教育质量的结论．     

基于递阶监督的一类多模型自适应控制

针对包含多个子系统的复杂系统,在控制中若使整个系统及子系统的性能最优,常规的控制方法难以实现.在采用一类多模型方案后,提出一种递阶智能监督控制策略,利用模糊神经网络、模糊决策构成了递阶控制的组织级和协调级.经过对混合动力汽车(HEV)的多能源动力总成控制系统进行的仿真研究,表明了该方法的有效性.     

基于CMIP5多模式集合预估贵州省干旱时空变化

为了科学合理地预估干旱变化对水资源管理系统造成的影响,以贵州省为研究对象,标准化降水蒸散指数(SPEI)为监测指标,结合国际耦合模式比较计划第5阶段(coupled model intercom-parison project 5,CMIP5)多模式集合数据资料,综合分析了2020—2100年贵州省干旱变化趋势及时空演...     

Phyllosilicates on Mars and implications for early martian climate

The recent identification of large deposits of sulphates by remote sensing and in situ observations has been considered evidence of the past presence of liquid water on Mars. Here we report the unambiguous detection of diverse phyllosilicates, a family of aqueous alteration products, on the basis of observations by the OMEGA imaging spectrometer on board the Mars Express spacecraft. These minerals are mainly associated with Noachian outcrops, which is consistent with an early active hydrological system, sustaining the long-term contact of igneous minerals with liquid water. We infer that the two main families of hydrated alteration products detected-phyllosilicates and sulphates--result from different formation processes. These occurred during two distinct climatic episodes: an early Noachian Mars, resulting in the formation of hydrated silicates, followed by a more acidic environment, in which sulphates formed.     

空中交通流量预测的人工神经网络和回归组合方法

为了寻找合适的空中交通流量预测方法,在综合回归预测方法和人工神经网络预测方法优点的基础上,提出采用组合预测方法的思想,并基于多元线性回归模型确定组合方法的权重系数。以北京管制区大王庄导航台流量预测为实例,分析结果表明:组合预测方法对实际流量有好的拟合度,能提高人工神经网络的泛化能力,并减小预测的误差,即总体上不仅优于传统的回归预测方法,也优于单独的人工神经网络预测方法。组合方法为空中交通流量的预测提供了一种可靠而有效的新途径。     

关于气候变化的哲学思考

从哲学的基本原理出发,引用地史及水文气象资料探讨了全球气候变化问题,指出全球气候一直在变化;气候变化的动力主要在天在地而不在人;当今的气候变化可能只是气候变化总过程中的一个波动阶段而非永远的趋势,且其变幅并未超出历史上气候变化的范畴。因此,不能断言全球气候变暖是由于人为排放CO2所致。所以对于不同时空条件下的气候变化应当具体矛盾具体分析具体解决,进而提出了中国应对气候变化的对策建议。     

基于多模态和加权支持向量机的热轧轧制力智能预报

为了提高热轧生产过程精轧机组的轧制力预设定精度,需要对轧制力进行高精度的预报.本文通过机理公式计算出轧制力的近似值,然后采集大量的实际生产数据修正轧制力预报值.首先利用聚类方法区分不同的生产状态,其次在相同生产状态下采用加权最小二乘支持向量机计算轧制力的修正系数,最后采用乘法方式修正轧制力,达到高精度的轧制力预测.结果表明,轧制力预报的平均相对误差为3.2%,满足现场的生产要求.     

基于灰色关联分析的季节性民航货运量预测

为更精确地预测月度航空货运量,提出组合模型预测方法.该模型由季节GM(1,1)和季节ARIMA乘积模型构成,它结合了该2种模型中时间序列预测的优点.灰色模型GM(1,1)能准确反映时间序列的增长趋势;ARIMA乘积模型对季节特征有较好的拟合效果.依据霍尔特温特预测模型计算季节性GM(1,1)模型的季节指数,并用灰色关联分析求出组合预测中的权值.组合预测模型的平均相对误差为0.62%,而季节性GM(1,1)模型和ARIMA乘积模型的平均相对误差分别为4.49%和-3.16%.预测分析结果说明,该模型的非线性曲线拟合精度和预测精度明显高于单个模型,可较好地反映系统的动态性和运量的季节时序关联性,为季节性时间序列预测提供了新的途径.     

Squeezing bandwidth controllable twin beam light and phase sensitive nonlinear interferometer based on atomic ensembles

We review our recent experimental progress in quantum technology employing amplification effect of four-wave mixing in a rubidium vapor. We have produced an intensity difference squeezed light source at frequencies as low as 1.5 kHz which is so far the lowest frequency at which squeezing has been observed in an atomic system. Moreover, we find that the bandwidth of our squeezed light source can be controlled with light intensity pumping. Using our non-classical light source, we have further developed a nonlinear Mach-Zehnder (MZ) interferometer, for which the maximum fringe intensity depends quadratically on the intensity of the phase-sensing field at the high-gain regime, leading to much better sensitivity than a linear MZ interferometer in which the beam splitters have the same phase-sensing intensity. The quantum technologies developed by our group could have great potential in areas such as precision measurement and quantum information.     

High-latitude influence on the eastern equatorial Pacific climate in the early Pleistocene epoch

Many records of tropical sea surface temperature and marine productivity exhibit cycles of 23 kyr (orbital precession) and 100 kyr during the past 0.5 Myr (refs 1-5), whereas high-latitude sea surface temperature records display much more pronounced obliquity cycles at a period of about 41 kyr (ref. 6). Little is known, however, about tropical climate variability before the mid-Pleistocene transition about 900 kyr ago, which marks the change from a climate dominated by 41-kyr cycles (when ice-age cycles and high-latitude sea surface temperature variations were dictated by changes in the Earth's obliquity) to the more recent 100-kyr cycles of ice ages. Here we analyse alkenones from marine sediments in the eastern equatorial Pacific Ocean to reconstruct sea surface temperatures and marine productivity over the past 1.8 Myr. We find that both records are dominated by the 41-kyr obliquity cycles between 1.8 and 1.2 Myr ago, with a relatively small contribution from orbital precession, and that early Pleistocene sea surface temperatures varied in the opposite sense to local annual insolation in the eastern equatorial Pacific Ocean. We conclude that during the early Pleistocene epoch, climate variability at our study site must have been determined by high-latitude processes that were driven by orbital obliquity forcing.     

基于时间序列季节调整的家用空调出口分析

家用空调出口量的数据序列中存在明显的季节效应,这会影响对家用空调出口整体趋势的分析及判断．针对这个问题,文章基于X—11模型对家用空调出口量的数据序列进行季节调整,消除其中的偶然因素,并利用SAS软件编程进行了实证分析．结果表明：2002年开始,我国空调出口量有非常显著的线性递增趋势,2008年下半年出现了明显的下滑,2009年初开始略有回升．     

基于灰色预测模型的全球气候变化趋势预测

考虑地球吸热、散热和海洋表面温度等因素对气候的影响,建立多变量灰色预测模型,预测未来气候变化趋势.考虑全球与局地之间是整体与部分的关系,建立基于多变量灰色预测的线性回归模型,判断全球气候变化与局地"极寒现象"之间是否存在关联性.     

Influence of mean climate change on climate variability from a 155-year tropical Pacific coral record

Today, the El Ni?o/Southern Oscillation (ENSO) system is the primary driver of interannual variability in global climate, but its long-term behaviour is poorly understood. Instrumental observations reveal a shift in 1976 towards warmer and wetter conditions in the tropical Pacific, with widespread climatic and ecological consequences. This shift, unique over the past century, has prompted debate over the influence of increasing atmospheric concentrations of greenhouse gases on ENSO variability. Here we present a 155-year ENSO reconstruction from a central tropical Pacific coral that provides new evidence for long-term changes in the regional mean climate and its variability. A gradual transition in the early twentieth century and the abrupt change in 1976, both towards warmer and wetter conditions, co-occur with changes in variability. In the mid-late nineteenth century, cooler and drier background conditions coincided with prominent decadal variability; in the early twentieth century, shorter-period (approximately 2.9 years) variability intensified. After 1920, variability weakens and becomes focused at interannual timescales; with the shift in 1976, variability with a period of about 4 years becomes prominent. Our results suggest that variability in the tropical Pacific is linked to the region's mean climate, and that changes in both have occurred during periods of natural as well as anthropogenic climate forcing.     

基于WRF/UCM的城市气候高分辨率数值模拟研究

以沿海城市大连2015年7月3日2时至7月4日2时的晴朗高温天气为研究背景,利用WRF/UCM以1km的高分辨率进行了城市气候数值模拟.结果表明:海风、山体对城市热岛有明显的缓解作用;中心城区受山地影响,形成了管道风效应;模拟期间城市热岛中心位于大连开发区一带,热岛强度最高达6.9℃,出现在2015年7月3日19时30分.将模拟结果与两个气象站和现场观测值进行了对比,发现模拟值与观测值变化趋势基本一致,地面温度场模拟结果优于风场模拟结果.温度场误差最大-3.10℃,最小0.08℃;平均误差最大0.88℃,最小0.52℃;均方根误差最大1.23℃,最小0.63℃.对于大尺度的城市气候研究而言误差在可接受的范围之内.对相应的缓解城市热岛的城市规划策略也进行了初步探讨.     

Inter-hemispheric comparison of climate change in the last millennium based on the ECHO-G simulation

The commonality and difference in the variations of temperature and precipitation between the Northern Hemisphere （NH） and Southern Hemispheres （SH） in the last millennium are investigated by analysis of the millennium simulation with the ECHO-G coupled climate model. The NH mean temperature variations are generally consistent with those of the SH counterpart on the interannual, decadal and centennial time scales. But, the transition times between the medieval warm period （MWP）, the little ice age （LIA）, and the present-day warm period （PWP） in the NH leads that in the SH; and the anomaly amplitude in the NH is significantly larger than the SH counterpart. For the precipitation variations, the NH mean precipitation varies in-phase with the SH mean precipitation on decadal and centennial scales （mainly in the mid-high latitudes） but out-of-phase on the interannual scale （mainly in the low latitudes）. During the MWP the warming has comparable amplitude in the NH and SH; however, during the PWP the NH warming is considerably stronger than the SH warming. Further, the present-day temperature rises in the NH high latitudes but decreases in the SH high latitudes, which is very different from the warming pattern during the MWP. Since during the MWP the greenhouse gases （GHG） concentration stayed at a low level, we infer that the present-day opposite temperature tendency in the high latitudes between the two hemispheres may be related to the increase of the GHG concentration.     

基于气候和土壤要素的中国耕地适宜性指数构建

中国历史土地利用的重建工作主要分为数据重建和空间重建,而建立具有空间指示作用的参数对于历史土地利用的空间重建具有举足轻重的指示意义.本文基于此想法,参考前人经验,构建了一套耕地适宜性指数,作为历史土地利用空间重建的基础.首先通过分析影响耕地时空分布的多种自然要素和人文因素,从中厘定土壤和气候这2个关键要素,然后基于此构建了一套计算耕地适宜性指数的方法.通过获取的气候适宜性与土壤适宜性的空间分布图与实际土地利用的相关性分析验证了这2个要素的一定代表性.本文最终的结果代表自然状态下耕地分布的最初可能性,具体特征有:1)对耕地分布起影响的气候适宜性分为4个等级的块状分布;2)对耕地分布有影响的土壤适宜性比较零散,但是大体还是以秦岭-淮河一线为分界线,呈现北高南低的分布;3)对于不同地区耕地分布,影响的主导因素有区别,西北为土壤要素,东南为气候要素;4)耕地适宜性最高的地区基本集中在华北平原、长江中下游平原区域,而青藏高原地区的适宜性最低.结合人口、经济等因素,这样一套耕地适宜性分布图对历史土地利用空间分布有重要的空间指示作用.